This invention relates to automatic rangefinders of the type generally described in U.S. Pat. No. 4,002,899 assigned to Honeywell, Inc. Such automatic rangefinders and focusing systems include two optical paths that bring light from the subject to photosensitive detectors. Such detectors are photosensitive devices and as such respond to the fact that both optical systems are aligned with one another and are directed toward the same subject. This alignment is called coincidence and generates a pulse from the photosensitive detector which can be used to adjust the focus of the main camera lens. One of the paths is fixed relative to the rangefinder and the other is movable so as to scan the image. The rangefinding is accomplished by triangulation and comparison of the image from the fixed path with an image from the scanned path. Scanning in these types of rangefinders is normally accomplished by use of a movable mirror (oscillating) to cover the field of view (angular) of the image. The use of such mirrors is cumbersome and does not permit an easy connection for feedback from the main lens. In addition, moving mirror surfaces cause a problem in that the angle of the scan has to be doubled in order to effectively cover the field of view.
It is an object of the present invention to replace the scanning mirror with a movable optic which is responsive to the position of the lens and the angular field of view of the subject.
It is a further object of the invention to simplify the structure required to oscillate or scan the subject and thereby improve the reliability and lower the cost of the mechanism for such scanning apparatus.